Cat Behavior - why aren't my boys mutually grooming each other or sleeping together a

Discuss Cat Behavior - why aren't my boys mutually grooming each other or sleeping together a on the - 'Cat Behavior' forum of I-Love-Cats. We are the place for all talk about 'Cat Behavior - why aren't my boys mutually grooming each other or sleeping together a'. My two boys I got as kittens, both Siamese, used to get along very well. They used to mutually groom each other all the time, sleep together, and play, chasing ...

Cat Behavior - why aren't my boys mutually grooming each other or sleeping together a

My two boys I got as kittens, both Siamese, used to get along very well. They used to mutually groom each other all the time, sleep together, and play, chasing each other around the house in a friendly way. Now they never sleep together, mutually groom and are biting and mounting each other regularly, perhaps to work out a dominant issue. Yesterday they actually started to hiss at each other with an ears back aggressive pose. Why the change?